Piston oil squirters in NASCAR engines

[englertracing]

Amazing we are talking about an engine that runs between 8000 and 9000. Why people think the Normal engine is even close really has me flabbergasted.

I dont think rpm qualifies the need or lack there of for squirters. Could be useful for high load engines regardless of rpm like a boat engine. Turbo and blower engines would benefit from cooler piston temperatures.

[PSA]

Amazing we are talking about an engine that runs between 8000 and 9000. Why people think the Normal engine is even close really has me flabbergasted.

I dont think rpm qualifies the need or lack there of for squirters. Could be useful for high load engines regardless of rpm like a boat engine. Turbo and blower engines would benefit from cooler piston temperatures.

Correct, it's a matter of how much heat that is pushed into the piston, that's why even low revving diesel engines can need them.
Looking at other things than just plain durability or avoiding catastrophic failures, I wonder how much it might help to shorten the warm up time on the oil and if there's any reduction in longtime wear from possibly keeping the piston at a more stable size (in regards of heat expansion).

[hoffman900]

Every high performance and purpose built race engine uses piston oil squirters because it keeps the pistons cool which allows more aggressive tunes, thinner rings, and in regards to oiling allows for more crankcase vacuum.

Blocking them off is really not seeing the forest for the trees and it doesn’t have to be a high rpm engine to see benefits.

[Mike Laws]

Every high performance and purpose built race engine uses piston oil squirters because it keeps the pistons cool which allows more aggressive tunes, thinner rings, and in regards to oiling allows for more crankcase vacuum.

Blocking them off is really not seeing the forest for the trees and it doesn’t have to be a high rpm engine to see benefits.

Correct and more. In the mid 90's - crankcase vacuum was "discovered" by the Cup engine builders to increase power. The vacuum also dried the wrist pin/piston relationship to the point of failure. I was commissioned by one of the teams to help, so the main web mounted jet system began. The first 1000+ jets used a .020" hole size. Wrist pin failures immediately went away, however there was a collateral gain too. Piston cooling. Soon, the hole size increased to .026" and eventually to .040". .040" was the maximum size for the jet diameter integrity. (Note that we tried a spring-loaded jet for a short while in order to shut-off flow at low rpm. This jet was short-lived because the O.D. needed to house an adequate spring/poppet assembly was too large, resulting in main web cracking.) The larger discharge hole was able to flow more heat from the piston. Oil stream direction was toward the exhaust side of the piston at mid-stroke. It was also determined that constant flow was desired even at low RPM's because the piston would cool even more under deceleration. (This is why idle oil pressure was often under 10 psi on these engines.) The main-web mounted system was eventually replaced by multiple jets in order to flow as much heat out of the piston as possible. Piston cooling provided wrist pin lubrication and piston cooling, which allowed for more aggressive tunes and increased fuel mileage - as those engines relied less on intake charge cooling. It was a win-win-win...

It was also interesting to keep up with the aggressiveness of each team. I was making jets for all of the teams and therefore knew what each team was using. One Ford team got very aggressive early on with hole size, while the other teams stayed in the middle. This went on for a few years until all were using .040" discharge holes and asking for more.

Some might also remember before/during this time that the Ford's made more power, but also had worse mileage, then it seemed like overnight, one of the Ford teams began getting better mileage than the GM's. It was the piston oilers and a progressive mindset.

Fun times...

[GARY C]

Every high performance and purpose built race engine uses piston oil squirters because it keeps the pistons cool which allows more aggressive tunes, thinner rings, and in regards to oiling allows for more crankcase vacuum.

Blocking them off is really not seeing the forest for the trees and it doesn’t have to be a high rpm engine to see benefits.

Correct and more. In the mid 90's - crankcase vacuum was "discovered" by the Cup engine builders to increase power. The vacuum also dried the wrist pin/piston relationship to the point of failure. I was commissioned by one of the teams to help, so the main web mounted jet system began. The first 1000+ jets used a .020" hole size. Wrist pin failures immediately went away, however there was a collateral gain too. Piston cooling. Soon, the hole size increased to .026" and eventually to .040". .040" was the maximum size for the jet diameter integrity. (Note that we tried a spring-loaded jet for a short while in order to shut-off flow at low rpm. This jet was short-lived because the O.D. needed to house an adequate spring/poppet assembly was too large, resulting in main web cracking.) The larger discharge hole was able to flow more heat from the piston. Oil stream direction was toward the exhaust side of the piston at mid-stroke. It was also determined that constant flow was desired even at low RPM's because the piston would cool even more under deceleration. (This is why idle oil pressure was often under 10 psi on these engines.) The main-web mounted system was eventually replaced by multiple jets in order to flow as much heat out of the piston as possible. Piston cooling provided wrist pin lubrication and piston cooling, which allowed for more aggressive tunes and increased fuel mileage - as those engines relied less on intake charge cooling. It was a win-win-win...

It was also interesting to keep up with the aggressiveness of each team. I was making jets for all of the teams and therefore knew what each team was using. One Ford team got very aggressive early on with hole size, while the other teams stayed in the middle. This went on for a few years until all were using .040" discharge holes and asking for more.

Some might also remember before/during this time that the Ford's made more power, but also had worse mileage, then it seemed like overnight, one of the Ford teams began getting better mileage than the GM's. It was the piston oilers and a progressive mindset.

Fun times...

I've run your system on SBC nitrous engines with .024 and .031 jets but never had an oil pressure issue, if anything I still had more than I wanted.

[Mike Laws]

I've run your system on SBC nitrous engines with .024 and .031 jets but never had an oil pressure issue, if anything I still had more than I wanted.

Good decision. Cooler pistons widens the tuning range w/nitrous... Open the jets to .040". Let it flow.

[midnightbluS10]

Amazing we are talking about an engine that runs between 8000 and 9000. Why people think the Normal engine is even close really has me flabbergasted.

What's "the normal engine"? What are you even talking about? You think RPM is what determines the needs for squirters? Why? What, makes it apply to one engine but not "the normal engine", whatever that is?

[NewbVetteGuy]

Looking at other things than just plain durability or avoiding catastrophic failures, I wonder how much it might help to shorten the warm up time on the oil and if there's any reduction in longtime wear from possibly keeping the piston at a more stable size (in regards of heat expansion).

I’ve wondered that too. Does running piston oil squirters mean you should / can run tighter piston to wall clearances?

The big question still seems to be how much piston temp or EGT temp reduction squirters gain you…


Adam

[hoffman900]

Here is from Honda’s development on their V8 F1 engine circa 2008. Changing the design, they were able to take an additional 25* C out of the piston for the same volume of oil and were able to add back 5.5* of timing they had to take out to get the pistons to live. A lot of this work came from the rules banning MMC’s and their struggle to keep pistons from cracking, which was two fold because the weight things had to be with the rpm at the time and the rules requiring more mileage out of the engines.

B0FFF555-3705-4813-994B-9A27AD2D70AF.jpeg

[NewbVetteGuy]

Are there any piston features that make oil squirters more effective?

I heard a rumor that the weird grid pattern on the bottom of an LS9 piston potentially exists for the purpose of giving oil a longer contact time and potentially improving cooling...

I REALLY want to call B.S. on that one, but what to do I know?


[Edit] THE PLOT THICKENS! Ford Ecotech also with squirters and also with "waffle" pattern on bottom of piston....



The great piston bottom texture debate? -Is a burr finish on a piston bottom best for oil squirters?

Adam

[NewbVetteGuy]

Dannobee posted a link to a 300 page E-book from Mahle that is just a WEALTH of information on piston temperatures, temp gradients, cooling methods and how effective they are at reducing certain parts of pistons (with TONS of FEA temp gradient diagrams and a mind-boggling amount of research in one PDF), here: https://fdocuments.in/document/pistons- ... tml?page=1

Most of the heat section is focused on Diesel engines and pistons for obvious reasons, but plenty of good content for any engine, IMHO.

Things I learned:
There can be LARGE heat gradients across a piston top and certainly through the piston; these heat gradients can cause the piston to slightly deform
Types of piston cooling:

• No Cooling -cool via ring contact with bore wall and random windage
• Spray jet cooling (wide spray angles should be used on regular pistons; narrow spray angles for pistons with cooling channels built in) -20C reduction in piston top, but there's detailed temp gradient diagrams showing the difference in each part of a piston
• Cooling Channels (can be salt casted in to the piston, cooled ring carriers, machined cooling channels) -salt core can reduce temps at the bowl rim by 20C and the top ring land by 10C vs. spray jet cooling

Pg 98 has a charge and a formula that shows much heat can be moved with a given volume of oil and a given per cylinder heat output with the amount of allowed temp rise in the oil as another factor. -Way beyond me to use the formula but maybe useful to someone.
-It provides a nice example showing that to remove 8% of the output power heat, with a 30C increase in oil temps, you need an oil flow rate with a traditional oil squirter (Spray jet) of 4.4 kg of oil per kWh of heat removed


There's also a fantastic chart showing the other factors that can increase the first ring land temps and by how much in table 7.3 on pg 136.

I found this chart particularly interesting.
[*]It showed that a 10C drop in coolant temps drives a 4-6C drop in the temp in the 1st ring groove
[*][*]A 10C drop in engine oil temps (Without any kind of piston oilers) drove a 1-2C drop in the 1st ring groove temps
[*]A 10C drop in charge air temps drove a 1.5-3C drop in the 1st ring groove temps
[*]A spray nozzle on a connecting rod's big end would drive an 8C - 15C temp reduction in the side of the piston that it's spraying
[*]A salt core cooling channel cast into the piston with narrow angle piston oil squirters dropped temps by 25C - 50C in the 1st ring grove
[*] Every 10C drop in the cooling oil then drove a further 4-7C drop in the 1st ring groove


Cool to see the relative drops in part of the piston from some of the different methods.
Still not sure how much drop in combustion temps / knock limit piston oil squirters gain you, but I can appreciate the complexity required to get to an answer better now and can see how more oil flow means pulling less heat out.



I also think I like the idea of pressure-regulated squirters more and more over time. You're making the engine less thermally efficient with a squirter so you can make more power when octane limited -the same as when you reduce engine coolant temps. -Just like with the electronic engine thermostats that can vary coolant temps, with piston oil squirters not functioning at low pressures and highway cruise RPMs, sure you have better oil pressure, but you also have a slightly more thermally efficient engine -I'm sure tiny difference, but if you're an OEM it makes sense.


Adam

[hoffman900]

Pistons with oil galleries in them have been used for a long time, Cosworth and others used them in the turbo-charged F1 engines in the 1980s.

They're mentioned here (a small part from a full length documentary): https://www.youtube.com/watch?v=kAn4ppQ_fQo

As for performance benefits, I don't think it's something you're going to calculate or simulate without a lot of measured data, but it is a fundamental part modern engine design and none would live at their power levels, save for a drag race application, for any amount of time. I think most pro road race and pro oval track engines need to go about 3000 miles or more now, and some are doing it at power levels near 300hp/L (4.9hp/ci).

[Dan Timberlake]

Are there any piston features that make oil squirters more effective?

I heard a rumor that the weird grid pattern on the bottom of an LS9 piston potentially exists for the purpose of giving oil a longer contact time and potentially improving cooling...

I REALLY want to call B.S. on that one, but what to do I know?


[Edit] THE PLOT THICKENS! Ford Ecotech also with squirters and also with "waffle" pattern on bottom of piston....



The great piston bottom texture debate? -Is a burr finish on a piston bottom best for oil squirters?

Adam

Those pictures look like smooth forged pistons vs lightly textured cast pistons

[digger]

Amazing we are talking about an engine that runs between 8000 and 9000. Why people think the Normal engine is even close really has me flabbergasted.

I'm partly with you in that for sure there are benefits but it is a horses for courses thing, if my "normal" engine i.e. weekend street driver on pump fuel with moderate CR that needs to cover alot of miles doesn't see WOT for more than ~10sec at a time there is potentially alot of cost and custom development to make use of these advantages discussed. Most of which will provide little tangible benefit for this application when currently not tune limited, fuel consumption at WOT is not an issue, not running crankcase vacuum as custom dry sump is $$$$ and aftermarket vacuum pump are not a high mileage device, no issue with pistons cracking etc

[af2]

Amazing we are talking about an engine that runs between 8000 and 9000. Why people think the Normal engine is even close really has me flabbergasted.

What's "the normal engine"? What are you even talking about? You think RPM is what determines the needs for squirters? Why? What, makes it apply to one engine but not "the normal engine", whatever that is?

As in the typical 1/4 per mile at a time running from 9.50 to 6.50. That's all.